Hi Jeffrey, sorry for the late reply. On 08.11.2012 19:54, Jeffrey Barish wrote: > On Wed 07 November 2012 10:01:14 Daniel Mack wrote: >> On 07.11.2012 00:54, Jeffrey Barish wrote: >>> I guess that snd_usb_pcm_prepare is called by the core usb system to >>> prepare the snd driver. Anyway, snd_usb_pcm_prepare calls >>> configure_endpoint with a substream. Then configure_endpoint calls >>> snd_usb_endpoint_set_params with the data endpoint that corresponds to >>> the substream. snd_usb_endpoint_set_params calls data_ep_set_params with >>> the data ep and data_ep_set_params sets nurbs to 2 for the data endpoint. >>> >>> snd_usb_endpoint_set_params has code to call sync_ep_set_params when the >>> endpoint is type sync. sync_ep_set_params sets nurbs to 4 (why?). >>> However, snd_usb_endpoint_set_params never invokes the call to >>> sync_ep_set_params because ep->type is always data. Back up: >>> snd_usb_endpoint_set_params is called from configure_endpoint. It is >>> called from an if block contingent on the substream's having a sync >>> endpoint. It does. However, the call to snd_usb_endpoint_set_params >>> passes subs->data_endpoint as the first argument, so >>> snd_usb_endpoint_set_params simply repeats the operations it performed as >>> a result of the previous invocation. I presume that the first argument >>> to the second call to snd_usb_endpoint_set_params should be >>> subs->sync_endpoint. >> Eh. You clearly spotted a bug here. The rally interesting thing is that >> that it didn't bite us earlier, as it's in since 3.6. > > Here's the diff. I can't figure out how to submit a patch. > > --- sound/usb/pcm.c.orig 2012-11-08 11:43:57.309732860 -0700 > +++ sound/usb/pcm.c 2012-11-08 11:41:06.512420658 -0700 > @@ -456,7 +456,7 @@ static int configure_endpoint(struct snd > return ret; > > if (subs->sync_endpoint) > - ret = snd_usb_endpoint_set_params(subs->data_endpoint, > + ret = snd_usb_endpoint_set_params(subs->sync_endpoint, > subs->pcm_format, > subs->channels, > subs->period_bytes, Thanks - I just sent out a patch for this. Daniel ------------------------------------------------------------------------------ Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
